Can you provide a summary of the size impact to this change? What I am looking for is the base image size, final image size and the original image size. Having this for the debian and ubuntu amd64 images would be sufficient.

Image Size Summary (on disk)

Focal

Buster

I just realized that buster SDK is now based on buster-slim. I suppose we should change its tag to be buster-slim now?

I just realized that buster SDK is now based on buster-slim. I suppose we should change its tag to be buster-slim now?

Yes, I think so.

Here's a comparison of the benefits these changes provide in terms of the download cost savings. The canonical scenario here is a multi-stage Dockerfile that builds and publishes an ASP.NET app (see the sample ASP.NET Dockerfile). The scenario involves first pulling the SDK image in order to build the application and then pulling the ASP.NET image to contain the published application. Before these changes, there was no layer sharing between the ASP.NET image and the SDK image. This was wasteful because the SDK image does contain ASP.NET bits; it just wasn't based on the ASP.NET image. With the changes that were made here, the SDK is now based on the ASP.NET image which means that once you've pulled the SDK image, you now essentially have the ASP.NET image as well. This provides substantial download savings when both images need to be pulled.

Focal

Net download savings: 100 MB (-30%)

Buster

Net download savings: 146 MB (-40%)